Nearly four months since Tavern on the Green went dark, there’s no telling when maybe new license-holder Dean Poll will reopen the landmark Central Park eatery.

The historic buildings, shorn of their crystal and brass, are rotting by the week. Meanwhile, Poll’s Boathouse Café, just north, snatches up Tavern’s exiled customers.

Isn’t this nuts? Sources say Mayor Bloomberg is fed up with the shambles, but it’s entirely of his own making. He and the Parks Department decided previous Tavern operator Jennifer LeRoy had to go, whether or not it made sense.

So, the city sent out a “request for proposals” a year ago with stipulations that scared normal restaurateurs off in droves. Now, Poll and Local 6 of the New York Hotel Trades Council are locked in talks with no end in sight over a new contract. Until there is one, the city won’t give Poll the keys.

Two months ago, Bloomberg finally turned red for having turned the thriving venue into a black hole. He sent his A-team in to mediate.

The squabble is mostly over the union’s impossibly onerous work rules, but nobody knows the nuts and bolts. A shut-up-or-else gag order from Bloomberg has muffled Poll and normally talkative Local 6 boss Peter Ward.

Meanwhile, there’ll be no Mother’s Day in the Crystal Room, no dancing in the beautiful garden.

Tavern had lousy food. I’m still getting over a memorably impenetrable cut of lamb served under the stars. But it was indispensable to the city’s celebratory life — such as the New York City Marathon, which might have to find a new finish line come November.

Although LeRoy had let the place run down, the city could have named its price for her to stay. But it wanted anyone but her to create “synergy” with the park, whatever that meant. Poll pledged $25 million on a new design. He’s silent as to where the money would come from, and the city’s just as secretive about the design.

The city’s terms “drove off everybody that was sane,” says Zagat Survey’s Tim Zagat, ex-chairman of the city’s Convention & Visitors Bureau. Worse, the request for proposal basically required an operator to deal with Local 6 on its terms.

“People don’t realize the union owns this deal,” says Strip House and Michael Jordan’s owner Peter Glazier. For sure. But Poll took the field knowing what the rules were.

It’s not like there was no warning. In 2007, city Comptroller Bill Thompson claimed that Poll scammed the city by undercounting annual Boathouse revenue by $2.4 million. How Poll made it up remains vague.

When the city trumpeted Poll’s anointing last Aug. 29, I wrote that all he had was an agreement to hold talks over precise license terms. I’ve since called it “no deal at all” and a “train wreck.”

What a pity. Even in its tormented last year, Tavern took in $27 million — the nation’s second-highest restaurant gross.

One place clearly not hurt by Tavern’s shutdown is Poll’s Boathouse — the park’s only other indoor-outdoor dining venue, and said by insiders to be prospering.

Bloomberg needs to lock Poll and Ward in a room until they strike a deal. Otherwise, Ground Zero will be rebuilt before Tavern serves its next leather lamb chop.